Telephone-exchange system.



s. B. WILLIAMS, JR. TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED SEPT. 3| l9l5.

Patented Nov. 7, 1916.

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SAMUEL B. WILLIAMS, JR., OF BROOKLYN, NEW YORK, ASEEIGNOR, BY MESNE ASSIGN- MENTS, TO WESTERN ELECTRIC COMPANY, INCORPORATED, A CORPORATION OF NEW YORK.

' TELEPHONE-EXCHANGE SYSTEM.

Application filed September 13, 1915.

To all L ham it may concern Be it known that I, SAMUEL B. WILLIAMS, Jr., a citizen of the United States, residing at Brooklyn, in the county of Kings and State of New York, have invented certain new and useful Improvements in Telephone- Exchange Systems, of which the following is a full, clear, concise, and exact description. a

This invention relates to telephone exchange systems, and more particularly to circuit arrangements for selector switches employed in automatic telephone exchanges.

It is the object of this invention to provide improved means for controlling the restoration of a selector switch if all the outgoing lines or trunks in the selected group have been found busy. 7

According to one feature of this invention the switch may be restored under the control of the selected outgoing line if the connection has been successfully established, means being provided for operating the restoring means under the control of thecalling line if all the outgoing lines of the selected group have been found busy.

According to another feature of this invention an electromagnetic means, such as a side switch, controlling the extension of a calling line to contacts of a selector switch, is operated upon the seizure of an idle outgoing line, the actuation of said electromagnetic means being prevented if all the outgoing lines in the selected group test busy.

The drawings represent the circuit ar range1nent of an automatic telephone exchange system, and, more in detail, that of a selector switch employed in the establishment of connections, only so much being shown of the circuits and apparatus as is necessary for a clear understanding of this invention. i

The subscriber at station 1, desiring to obtain a connection with a sub-station 2, removes his receiver from the switchhook, causing thereby inthe well-known manner the extension of his line to a trunk leading to a selector switch 3. A circuit is closed from grounded battery through the lefthand winding of a line relay 4, wiper 5 of an electromagnetic means, such as a side switch, associated with selector 3, the calling incoming line circuit, side-switch Wiper n the g t-hand winding of relay 4, to

Specification of Letters Patent.

Patented Nov. 7, 1916.

Serial No. 50,370.

ground. Relay 4 closes a circuit from ground through its armature and front contact and the winding of a slow-acting relay 7, to grounded battery, and through conductor 10, sideswitch wiper 11 and the winding of an escapement magnet 12, to grounded battery. Relay 4 closes also another circuit from ground through its armature and front contact, normal contact 13 controlled by selector 3, side-switch wiper 14, the winding of a slow-acting relay 15, and the secondary winding of an induction coil 16, to grounded battery. Magnet 12 closes a locking circuit for itself from grounded battery through its winding, side switch wiper S, the front contact and armature of magnet 12, conductor and the front contact and armature of line relay 4, to ground. The calling subscriber proceeds now to cause the setting of selector 3 by operating a calling device 17 provided at station 1 for producing a series of interruptions in the incoming line circuit. In response to the first interruption, line relay 4 releases its armature and breaks thus the circuits of relays 7 and and locking circuit of magnet 12. Relays 7 and 15 being slow to release, remain energized for a short period. Magnet 12, however, deenergizes, and moves the side-switch wipers into the second position. Upon the following closure of the line circuit, a circuit is established from grounded battery through the winding of a primary magnet 20, sideswitch wiper 21, the back contact and armature of magnet 12, conductor 10, and the front contact and armature of relay 4, to ground. In response to each energization of relay 4, magnet 20 will thus receive an impulse and cause the stepping of the movable contacts or brushes of selector 3 in a rotary direction to select the desired row of stationarycontacts in which trunks or outgoing lines terminate. Upon each attraction of the armature of relay 4, the circuit of relay 7 was also again established, and this relay remains energized during the vibration of the line relay armature. The circuit of relay 15 was changed, due to the opening of normal contact 13 and the closing of an oif-normal contact 22, as soon as selector 3 leaves its normal position. The circuit of relay 15 is closed upon each retraction of the armature of relay 4 from ground through the armature and back contact of this relay, oil-normal contact 22, side-switch wiper 14, the wmdmg oi relay 15, and the secondary wmding of induction coil 16, to grounded battery.

After the sending out of the desired series of impulses, relay 4 remains constantly energized, breaking thus the circuit of relay 15 which deenergizes and closes a circuit from ground through side-switch wiper 23, its back contact and armature, conductor 24, side-switch wiper 11 and the winding of magnet '12, to grounded battery. Magnet 12 becomes energized and moves now, upon energization, the side-switch wipers into position 3. A circuit is established from grounded battery through the wind ing, armature and back Contact of a secondary magnet 24:, side-switch wiper 21, the

tery and the idle trunks by a ground connection to stationary contact 25, it will'be seen that as soon as test brush 26 of selector 3 reaches the terminal 25 of an idle trunk, a circuit is established from such ground through terminal 25, brush 26, conductor 28, the armature and back'contact of 'relay 15, side-switch wipers 23 and 11. and the winding of magnet 12, to grounded battery. Magnet 12 thereupon becomes energized and moves the side-switch wipers into position 1, in which position magnet '24. and relay 4: are disconnected, and the incoming line is extended by means of side-switch Wipers 5 and 6 to the selected outgoing line. The calling subscriber may cause now the setting of further apparatus for completing theestablishment of the connection to the called station 2. The sleeve or test wire 28 is extended to the next switching apparatus through side-switch wiper 23 and the back contact and armature of relay 15. The deenergization of relay t causes the reaction of relay 7. Upon disconnection, ground is connected through terminal 25, brush 26, conductor 28, the armature and back con tact of relay 15, side-switch wiper 23, an cit-normal contact 27 of selector 3, and the winding of a restoring magnet 30, to grounded battery, no such ground connection ex isting during conversation. Magnet 30 becomes'energized and causes first the restoration of the sideswitch to normal, whereupon a locking circuit is established for this restoring magnet from grounded batter-v through its winding, off-normal contact 24, side-switch wiper 3 1, armature and'back contact of relay 7, and the. back contactand armature of relay l, to ground; Magnet 30 causes now the restoration of selector 3, said locking circuit remaining closed as long as contact 27 is closed, 2'. 0., until selector 3 reaches its normal position. 7

If all the outgoing lines in the selected group are busy, 2'. 6., upon the tenth vertical step of selector 3 (if a one hundred point selector is used), an over-run contact is closed. A circuit is established there upon from grounded battery, through the secondary winding of induction coil 16, the winding of relay 15, side-switch wiper l t (in position 3), contact 32, the calling in coming line circuit, side-switch wiper G, and the right-hand winding of relay 4, to ground. Relay 15 becomes energized and, by attracting its armature, opens the circuit which'was prepared for escape magnet 12,

"in order to prevent the energization of this magnet if the last trunk of the selected group becomes idle in the meantime. A busy tone is also applled to the callmg subscribers line through the primary and secondary windings of an induction coil 16 and the above traced circuit of relay 15. The calling subscriber, hearing the busy tone, restores his receiver for causing the deenergization of relay ahwhereupon a circuit is closed from ground through the armature and back conta ct, of this relay, the back contactand armature of relay 7, side-switch wiper 31, off-normal contact. 27 and the winding of restoringmagnet'30, to grounded battery. The restoring magnet controls thereupon the restoration of the side switch and selector 3 in the samemanner as above described. Thus, ifall the trunks of a selected group test busy, the side switch is prevented from moving into the fourth position, and, therefore, the control of the re-' lease of selector 3, instead of being transferred to the called party, remains with the calling party. If the callinglnsubscriber abandons the call "during the setting of selector 3 by hanging uphis receiver, relay l becomes deenergized and causes the reaction of relay 7, whereupon the last traced (31101111'1 of restoring magnet 30 is established, and the actuated mechanism is restored to normal. There is shown in the drawings 'at the armature of restoring magnet 30, an antisparking device 10 comprising a condenser, a resistance and a. grounded battery, which serves for preventing the. occurrence or sparks at the contacts of the operating magnets associated with selector 3.

What is claimed is:. V r 1.111 a telephone exchange "system, in-' coming lines and groups of outgoinglines, a selector switch for interconnecting the same, an electromagnet for operating said switch to select a group of outgoing lines, automatic means operative thereupon for controlling said switch to select an idle utgoing line in the selected group electromagnetic means for extending a calling line to said selector switch, a circuit extending over the selected outgoing lines for operating said electromagnetic means, a relay controlling said circuit, and means for actuating for causing said movable contacts to select an idle set in said row of stationary contacts, electromagnetic means for extending a calling line to said movable contacts, a circuit for said electromagnetic means extending through one of said movable contacts engaging a stationary contact, a relay adapted to be actuated by a circuit extending over a calling line and controlling the circuit of said electromagnetic means, a contact in the circuit of said relay, and means operative if all the stationary contacts of the selected row have been found busy for actuating the contact provided in the circuit of said relay.

In Witness whereof, I hereunto subscribe my name this 10th day of September A. D., 1915.

SAMUEL B. WILLIAMS, Jn.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. G. 

